not SOG but SCROG, SOG you generally want 1 short good stem not multiple

on forced flowering most plants will generally double in size, sativas alittle more, so if you have a 5' space subtract light and pot hight(aprox. 3-3.5' grow space)i would try to flower at 1-1.5'. but since lst you could go longer veg and height of plant can be bigger

to heat up the room either add alittle electric heater or if it were me i would add another light to raise temps

what is your intake system and exhaust system like?

and cold temps affecting bud, it depends on strain as to how it does with weather, ask seed bank condition plants like, as they have best knowledge of plants you have